System and method for testing fans

ABSTRACT

A fan test system includes a control module. The control module includes a temperature-speed table storing standard speeds at different temperatures of a fan, a counter loaded with a default value, and a fan speed control unit setting the time interval for obtaining the actual speed of a fan corresponding to a certain temperature. The fan speed control unit obtains the actual speed of the fan at every interval time, and determines whether the speeds obtained at predetermined continuous interval times are equal. The fan speed control unit obtains the standard speed of the fan according to the certain temperature if the speeds are equal. It indicates the fan is qualified in response to the actual speed being equal to the standard speed.

BACKGROUND

1. Technical Field

The present disclosure relates to a system and a method for testing fans.

2. Description of Related Art

In a conventional motherboard, a baseboard management controller (BMC) is always employed to control the speed of a fan to dissipate the heat of an electronic chip, such as a central processing unit (CPU), according to a certain temperature. Thus, it is critical to set right speeds of the fan at various temperatures, thereby to prevent the CPU from overheating. In order to determine whether the fan is qualified or not, a fan speed control (FSC) method is introduced to test the speed of the fan in accordance with the temperature, which consists of the following steps. First, a predetermined value is transmitted to the BMC to simulate the temperature of a chip, and the BMC delivers a pulse width modulation (PWM) signal corresponding to the predetermined value to the fan. Second, after a certain time, such as T1, the BMC obtains the actual speed of the fan through a TACH pin of the fan, and gets the standard speed corresponding to the predetermined value. Finally, the BMC determines whether the actual speed is equal to the standard speed. If the actual speed is equal to the standard speed, it indicates that the fan has passed the FSC test. Otherwise, the fan fails the FSC test. However, a certain time, such as T2, is taken for the fan to accelerate or decelerate to be stable after receiving the PWM signal from the BMC. If the time T1 is less than T2, it could be understood that the speed of the fan is unstable at the time T1, and the actual speed of the fan is changing at the time T1. Therefore, the result of the FSC test may be inaccurate.

Therefore, there is need for improvement in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present disclosure can be better understood with reference to the following drawing(s). The components in the drawing(s) are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawing(s), like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is a block diagram of an embodiment of a fan test system of the present disclosure.

FIG. 2 is a flowchart of an embodiment of a fan test method of the present disclosure.

DETAILED DESCRIPTION

FIG. 1, is an embodiment of a test system for a fan 20. The test system includes a control module 10 and an alarm circuit 30. In this embodiment, the control module 10 is a baseboard management controller (BMC).

The control module 10 includes a storage unit 100 storing a temperature-speed table, a fan speed control (FSC) unit 102, and a counter 104. The control module 10 outputs a pulse width modulation (PWM) signal to a pulse pin PWM of the fan 20, to control the speed of the fan 20 according to the temperature set by the control module 10 to simulate the temperature of a chip, such as central processing unit (CPU), and obtains the speed of the fan 20 through a speed pin TACH of the fan 20.

The alarm circuit 30 includes a light-emitting diode D. The anode of the light-emitting diode D is coupled to the control module 10, and the cathode of the light-emitting diode D is grounded.

The temperature-speed table includes the standard speeds of the fan 20 corresponding to different temperatures.

In the embodiment, the FSC unit 102 is used to set a temperature simulating the temperature of the CPU. The control module 10 transmits a PWM signal corresponding to the temperature set by the FSC unit 102, to control the speed of the fan 20. Therefore, it is convenient for the control module 10 to transmit various PWM signals corresponding to different temperatures, to automatically control the speed of the fan 20.

The FSC unit 102 is also used to set a default value of the counter 104 and a time interval of obtaining the actual speed of the fan 20. The FSC unit 102 obtains the actual speed of the fans 20 at every time interval, and determines whether the actual speeds of the fan 20 at two continuous time intervals are equal. A determination is made that the fan 20 is stable only when the actual speeds of the fan 20 at predetermined continuous time intervals summed to be equal to the default value of the counter 104. When the fan 20 is stable, the FSC unit 102 obtains the standard speed from the temperature-speed table according to the temperature, and determines whether the actual speed is equal to the standard speed. The fan 20 passes the FSC test if the actual speed is equal to the standard speed. If the actual speed is not equal to the standard speed, the control module 10 outputs an alarm signal of high level, such as logic 1, to the light-emitting diode D to make the light-emitting diode D emit light. Thus, it is easy to know if the fan 20 is qualified or not with a visual inspection.

Referring to FIG. 2, a fan test method of the present disclosure includes steps as follows.

In step S1, the FSC unit 102 sets a default value of the counter 104, a temperature, and an interval time of obtaining the actual speed of the fan 20.

During the FSC test, the FSC unit 102 sets a temperature to simulate the temperature of the chip, such as the CPU, the control module 10 transmits a pulse width modulation (PWM) signal to the pulse pin PWM of the fan 20 according to the temperature, to control the speed of the fan 20. The default value of the counter 104 indicates a sum of the predetermined continuous time intervals of the actual speeds of the fan 20 being equal.

In step S2, the FSC unit 102 obtains a first actual speed of the fan 20 set as a first speed.

In step S3, the FSC control unit 102 obtains a second actual speed of the fan 20 at every time interval set as a second speed.

In step S4, the FSC control unit 102 determines whether the first speed is equal to the second speed. If the first speed is equal to the second speed, step S5 is implemented, otherwise, step S6 is implemented.

In step S5, the counter 104 decreases by 1, and step S7 is implemented.

In step S6, the FSC control unit 102 sets the counter 104 to the default value, and sets the second speed as the first speed, the process returns to step S3. The fan 20 is unstable if the first speed is not equal to the second speed. Thereafter, the FSC control unit 102 sets the second speed as the first speed, and obtains a third actual speed of the fan 20 at every time interval by returning to step S3, and sets the third actual speed as the second speed. [0020] In step S7, the FSC control unit 102 determines whether the counter 104 is equal to 0. If the value of the counter 104 is not equal to 0, it indicates that the fan 20 is unstable. The process returns to step S3 to obtain the speed of the fan 20.

In step S8, the FSC control unit 102 obtains the standard speed from the temperature-speed table corresponding to the temperature.

In step S9, the FSC control unit 102 determines whether the actual speed is equal to the standard speed. If the actual speed is equal to the standard speed, step S11 is implemented, otherwise, step S10 is implemented.

In step S10, the FSC control unit delivers an alarm signal to the alarm circuit 30 to make the light-emitting diode D emit light, to show that the fan 20 is not qualified.

In step S11, it indicates that the fan 20 is qualified.

While the disclosure has been described by way of example and in terms of preferred embodiment, it is to be understood that the disclosure is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements as would be apparent to those skilled in the art. Therefore, the range of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements. 

What is claimed is:
 1. A test system for a fan, comprising: a control module transmitting a pulse width modulation signal to a pulse pin of the fan according to a certain temperature, and obtaining the actual speed of the fan, the control module comprises: a storage unit storing a temperature-speed table, wherein the temperature-speed table containing the standard speeds of the fan corresponding to different temperatures; a counter loaded with a default value; and a fan speed control unit setting a time interval for obtaining the actual speed of the fan; wherein the fan speed control unit obtains the actual speed of the fan at every time interval, and obtains the standard speed of the fan according to the certain temperature in response to the actual speeds of the fan being equal at predetermined continuous time intervals summed to the default value of the counter, thereby to represent the fan is qualified in response to the actual speed being equal to the standard speed.
 2. The test system of claim 1, further comprising an alarm circuit, wherein the alarm circuit comprises a light-emitting diode, an anode of the light-emitting diode is coupled to the control module, a cathode of the light-emitting diode is grounded, the fan speed control unit transmits an alarm signal to the alarm circuit to make the light-emitting diode emit light in response to the actual speed being not equal to the standard speed.
 3. The test system of claim 1, wherein the control module is a baseboard management controller.
 4. A test method for a fan, comprising: setting a certain temperature, a default value of a counter, and a time interval for obtaining an actual speed of the fan; obtaining a first actual speed of the fan corresponding to a first temperature, and setting the first actual speed as a first speed; obtaining a second actual speed of the fan at every time interval, and setting the second actual speed as a second speed; determining whether the first speed is equal to the second speed; decreasing the counter by 1 in response to the first speed equaling to the second speed; setting the counter to the default value, and setting the second speed as the first speed in response to the first speed being not equal to the second speed; determining whether the counter is equal to 0; obtaining the standard speed of the fan from a temperature-speed table according to the certain temperature in response to the counter being 0; determining whether the actual speed is equal to the standard speed; and indicating the fan is qualified in response to the actual speed equaling to the standard speed.
 5. The test method of claim 4, further comprising: delivering an alarm signal to an alarm circuit to alarm in response to the actual speed being not equal to the standard speed.
 6. The test method of claim 5, wherein the alarm circuit comprises a light-emitting diode, an anode of the light-emitting diode is employed to receive the alarm signal, a cathode of the light-emitting diode is grounded, the light-emitting diode emits light in response to receiving the alarm signal.
 7. The test method of claim 4, wherein the temperature-speed table is stored in a storage unit. 